2.4.2 Sentences

A
sentence
begins wherever a paragraph or previous sentence ends. The end of a sentence is defined as consisting of a sentence terminating character followed by two spaces or a newline.
Two
spaces are required to prevent abbreviations (such as Mr.) from being taken as the end of a sentence. Such abbreviations at the end of a line are taken as the end of a sentence. There may also be any number of closing delimiter characters between the sentence terminating character and the spaces or newline.